View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0032346 | Community | OCCT:Modeling Algorithms | public | 2021-05-06 12:26 | 2021-05-10 11:34 |
| Reporter | geuzaine | Assigned To | |||
| Priority | normal | Severity | minor | ||
| Status | new | Resolution | open | ||
| Platform | Mac | OS | OS | ||
| Product Version | 7.5.1 | ||||
| Summary | 0032346: Modeling Algorithms - Strange result of intersection | ||||
| Description | Dear OCCT team, I obtain strange results when I apply boolean operations between the two solids (a tapered cylinder and a sphere) contained in the attached BREP file ("two_volumes.brep"). For example, computing the intersection (BRepAlgoAPI_Common) leads to a self-overlapping spherical patch with loops on the bounding curves (see attached screeenshot "strange.png"). Thanks, Christophe | ||||
| Additional information and documentation updates | See https://gitlab.onelab.info/gmsh/gmsh/-/issues/1327 for the related bug report in Gmsh. | ||||
| Tags | No tags attached. | ||||
| Test case number | |||||
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two_volumes.brep (3,478 bytes) |
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strange.png (11,586 bytes) |
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But something wrong in your brep file, an error occurs when trying to open it with CAD Assisant. I made the same example with freecad : - the new brep file is imported in gmsh but when i activate swewing and fixing options, the sphere disappears. -i get a mesh using netgen (included in freecad). |
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EllispeAndSphere.png (50,853 bytes) |
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mesh.png (69,953 bytes) |
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two_volumes_with_freecad.brep (89,936 bytes) |
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Thanks for the testing! Your "two_volumes_with_freecad.brep" geometry is however not the same as "two_volumes.brep" : you have a straight cylinder (instead of a tapered cylinder), and the sphere is at another location. Attached is the file containing the union of the shapes from the original file ("two_volumes_union.brep"). Gmsh can produce a coarse mesh (similar to the one you obtained with Netgen) for this geometry. The issue is that if one refines, since the parametrization is self-overlapping, it will eventually lead to a self-overlapping mesh as well. |
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two_volumes_union.brep (17,140 bytes) |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2021-05-06 12:26 | geuzaine | New Issue | |
| 2021-05-06 12:26 | geuzaine | Assigned To | => msv |
| 2021-05-06 12:26 | geuzaine | File Added: two_volumes.brep | |
| 2021-05-06 12:26 | geuzaine | File Added: strange.png | |
| 2021-05-10 01:05 | mrbenson | Note Added: 0100836 | |
| 2021-05-10 01:07 | mrbenson | File Added: EllispeAndSphere.png | |
| 2021-05-10 01:23 | mrbenson | File Added: mesh.png | |
| 2021-05-10 01:24 | mrbenson | File Added: two_volumes_with_freecad.brep | |
| 2021-05-10 01:27 | mrbenson | Note Edited: 0100836 | |
| 2021-05-10 10:07 | geuzaine | Note Added: 0100840 | |
| 2021-05-10 10:07 | geuzaine | File Added: two_volumes_union.brep | |
| 2021-05-10 11:34 | kgv | Summary | Strange result of intersection => Modeling Algorithms - Strange result of intersection |
